1 /* 2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * https://www.openssl.org/source/license.html 8 * or in the file LICENSE in the source distribution. 9 */ 10 11 /* 12 * Confirm that if (d, r) = a / b, then b * d + r == a, and that sign(d) == 13 * sign(a), and 0 <= r <= b 14 */ 15 16 #include <stdio.h> 17 #include <openssl/bn.h> 18 #include <openssl/err.h> 19 #include "fuzzer.h" 20 21 /* 256 kB */ 22 #define MAX_LEN (256 * 1000) 23 24 static BN_CTX *ctx; 25 static BIGNUM *b1; 26 static BIGNUM *b2; 27 static BIGNUM *b3; 28 static BIGNUM *b4; 29 static BIGNUM *b5; 30 31 int FuzzerInitialize(int *argc, char ***argv) 32 { 33 b1 = BN_new(); 34 b2 = BN_new(); 35 b3 = BN_new(); 36 b4 = BN_new(); 37 b5 = BN_new(); 38 ctx = BN_CTX_new(); 39 40 OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL); 41 ERR_clear_error(); 42 43 return 1; 44 } 45 46 int FuzzerTestOneInput(const uint8_t *buf, size_t len) 47 { 48 int success = 0; 49 size_t l1 = 0, l2 = 0; 50 /* s1 and s2 will be the signs for b1 and b2. */ 51 int s1 = 0, s2 = 0; 52 53 /* limit the size of the input to avoid timeout */ 54 if (len > MAX_LEN) 55 len = MAX_LEN; 56 57 /* We are going to split the buffer in two, sizes l1 and l2, giving b1 and 58 * b2. 59 */ 60 if (len > 0) { 61 --len; 62 /* Use first byte to divide the remaining buffer into 3Fths. I admit 63 * this disallows some number sizes. If it matters, better ideas are 64 * welcome (Ben). 65 */ 66 l1 = ((buf[0] & 0x3f) * len) / 0x3f; 67 s1 = buf[0] & 0x40; 68 s2 = buf[0] & 0x80; 69 ++buf; 70 l2 = len - l1; 71 } 72 OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1); 73 BN_set_negative(b1, s1); 74 OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2); 75 BN_set_negative(b2, s2); 76 77 /* divide by 0 is an error */ 78 if (BN_is_zero(b2)) { 79 success = 1; 80 goto done; 81 } 82 83 OPENSSL_assert(BN_div(b3, b4, b1, b2, ctx)); 84 if (BN_is_zero(b1)) 85 success = BN_is_zero(b3) && BN_is_zero(b4); 86 else if (BN_is_negative(b1)) 87 success = (BN_is_negative(b3) != BN_is_negative(b2) || BN_is_zero(b3)) 88 && (BN_is_negative(b4) || BN_is_zero(b4)); 89 else 90 success = (BN_is_negative(b3) == BN_is_negative(b2) || BN_is_zero(b3)) 91 && (!BN_is_negative(b4) || BN_is_zero(b4)); 92 OPENSSL_assert(BN_mul(b5, b3, b2, ctx)); 93 OPENSSL_assert(BN_add(b5, b5, b4)); 94 95 success = success && BN_cmp(b5, b1) == 0; 96 if (!success) { 97 BN_print_fp(stdout, b1); 98 putchar('\n'); 99 BN_print_fp(stdout, b2); 100 putchar('\n'); 101 BN_print_fp(stdout, b3); 102 putchar('\n'); 103 BN_print_fp(stdout, b4); 104 putchar('\n'); 105 BN_print_fp(stdout, b5); 106 putchar('\n'); 107 printf("%d %d %d %d %d %d %d\n", BN_is_negative(b1), 108 BN_is_negative(b2), 109 BN_is_negative(b3), BN_is_negative(b4), BN_is_zero(b4), 110 BN_is_negative(b3) != BN_is_negative(b2) 111 && (BN_is_negative(b4) || BN_is_zero(b4)), 112 BN_cmp(b5, b1)); 113 puts("----\n"); 114 } 115 116 done: 117 OPENSSL_assert(success); 118 ERR_clear_error(); 119 120 return 0; 121 } 122 123 void FuzzerCleanup(void) 124 { 125 BN_free(b1); 126 BN_free(b2); 127 BN_free(b3); 128 BN_free(b4); 129 BN_free(b5); 130 BN_CTX_free(ctx); 131 } 132